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The Earth satellite, referred to as 'A10bMLz,' was first spotted by the Asteroid Terrestrial-impact Last Alert System (ATLAS) telescope in Hawaii, on Friday. Northolt Observatories found that the object (pictured) is 'extremely light-weight' but several meters across

A10bMLz was moving in an unusual retrograde orbit, instead of prograde orbit. It's orbiting 600 km above the Earth's surface but drifted as far as 1.4 times out from the moon

'This suggests that it is what is known as an "empty trash bag object,"' Northolt Branch Observatories explained in a Facebook post.

'A piece of light material (probably metallic foil), left over from a rocket launch.

'It is not clear yet when A10bMLz has been launched,' they added.

A10bMLz further puzzled astronomers once they noticed that it was travelling in retrograde orbit, instead of prograde orbit.

'It is orbiting the Earth in an unusual, retrograde orbit, at an average distance of 262,000 km,' Northolt Branch Observatories said.

'The orbit is highly elliptical, with a perigee just 600 km above the Earth's surface, and an apogee 1.4 times as far out as the Moon.'

Empty trash bag objects have been spotted by astronomers many times before, but A10bMLz surprised Northolt Branch Observatories due to its very distant and unpredictable orbit

WHAT IS SPACE JUNK?

There are an estimated 170 million pieces of so-called 'space junk' - left behind after missions that can be as big as spent rocket stages or as small as paint flakes - in orbit alongside some US$700 billion of space infrastructure.

But only 22,000 are tracked, and with the fragments able to travel at speeds above 27,000kmh (16,777 mph), even tiny pieces could seriously damage or destroy satellites.

However, traditional gripping methods don't work in space, as suction cups do not function in a vacuum and temperatures are too cold for substances like tape and glue.

Grippers based around magnets are useless because most of the debris in orbit around Earth is not magnetic.

Around 500,000 pieces of human-made debris (artist's impression) currently orbit our planet, made up of disused satellites, bits of spacecraft and spent rockets

Most proposed solutions, including debris harpoons, either require or cause forceful interaction with the debris, which could push those objects in unintended, unpredictable directions.

Scientists point to two events that have badly worsened the problem of space junk.

The first was in February 2009, when an Iridium telecoms satellite and Kosmos-2251, a Russian military satellite, accidentally collided.

The second was in January 2007, when China tested an anti-satellite weapon on an old Fengyun weather satellite.

Experts also pointed to two sites that have become worryingly cluttered.

One is low Earth orbit which is used by satnav satellites, the ISS, China's manned missions and the Hubble telescope, among others.

The other is in geostationary orbit, and is used by communications, weather and surveillance satellites that must maintain a fixed position relative to Earth.

Empty trash bag objects have been spotted by astronomers many times before, but A10bMLz surprised them due to its very distant orbit, Northolt Branch Observatories said.

Project Pluto, which makes planetarium software, compared the object's orbit to that of a plastic bag.

A10bMLz's unpredictable orbit is likely one of several reasons why astronomers are having trouble figuring out where the object came from.

'At present, we have no idea as to the origin of this object,' Project Pluto said.

'That's mostly because its past trajectory is really uncertain. As with an empty trash bag blowing down the street, it may zig and zag in unpredictable ways.

Predicting the artificial satellite's trajectory is currently impossible. Astronomers believe the object may burn up upon reentry into the Earth's atmosphere within a few months

'...I don't see any recent lunar flybys, and wouldn't speculate on when it might hit the earth or moon or leave the earth-moon system,' they continued.

Because the object is so lightweight, Northholt Branch Observatories said the object is easily pushed around by pressure from the sun's radiation.

This changes its 'orbit chaotically on time scales of days to weeks,' making it impossible to predict what direction it will move to in the future.

What's more, Northolt Branch Observatories believes the object may burn up in the Earth's atmosphere within a few months.